Electronic controllers are widely used in industrial automation and automotive applications, usually custom designed for specific groups of input sensors output devices and control applications. Configurable Electronic Controllers (CEC), as described, for example, in U.S. Pat. No. 7,096,073, entitled “Configurable Controller” filed by Burkatovsky on Sep. 22, 2005, are considered particularly versatile, enabling design of electronic controllers capable of measuring a variety of digital and analog sensors, as well as controlling a range of output devices such as motors, solenoids and lamps. The CEC flexibility on both input and output sides of the controller is achieved essentially by use of a configurable in/out interface.
H-Bridge is a well-known current load driver scheme, available in many practical configurations, such as for example types HIP4080AIB of Intersil and type LMD18200 of National Semiconductors.
The use of prior art H-Bridge module in a load driver and control circuitry is schematically shown in FIG. 1. As shown in FIG. 1, load 20 is of a type that requires bidirectional current control. Examples of which include, but are not limited to, a DC motor, stepper motors, or a thermoelectric cooler device. One circuit that is commonly used in the art to provide such bi-directional control is an H-Bridge module 12. For reliable H-Bridge current control it is advisable to have some kind of fast current protection mechanism. In the prior art system of FIG. 1, a protection current sensor 16 is used on a high side of H-Bridge module 12, in order to protect against any over current situation, such as may be caused by a short circuit, including a short between the wires 18 connecting load 20 to H-Bridge module 12, and Ground. When such over current is detected, controller 10 is turned off immediately by the electronic switch acting as an electronic fuse 22. In addition, a load control current sensor (value and direction) 14 is usually connected in a low side of H-Bridge module 12.
Controller 10 controls the current of load 20 by using, for example, known-in-the art pulse width modulation (PWM) based on locked anti-phase method, or using known-in-the-art pulse width modulation (PWM) based on sign & magnitude method.
FIG. 2 schematically illustrates, another well-known embodiment, a load driver and control circuitry for an H-Bridge module including: a configurable digital unit, such as a field programmable gate array (FPGA) based controller 10, a load control current sensor module 14 on the low-side of H-Bridge module 12 for load current control, a protection current sensor module 16 on the high-side of H-Bridge module 12, and an electronic fuse 22 as a current protection mechanism. As shown in FIG. 2, H-Bridge module 12 drives load 20 as a load.
Other known-in-the-art applications use a complex high-side current sensor for both current control and protection, based on a double sense method, which limits the pulse width modulation (PWM) functionality and the protection level as explained in the data sheet for the LMD18200 driver mentioned above.
The following patents and application publication describe various aspects of the use of H-Bridges in load control circuitry: U.S. Pat. No. 6,683,437 to Tierling, issued Jan. 27, 2004, entitled “Current Controlled Motor Amplifier System”; U.S. Pat. No. 6,147,545 to Marshall, issued Nov. 14, 2000, entitled “Bridge Control Circuit for Eliminating Shoot-Through Current”; U.S. Pat. No. 5,990,640 to Dwyer et al., issued Nov. 23, 1999, entitled “Motor Control Apparatus”; U.S. Pat. No. 5,642,247 to Giordano, issued Jun. 24, 1997, entitled “Automatic Fault Monitoring System and Motor Control System Incorporating Same”; U.S. Pat. No. 5,963,706 to Baik, issued Oct. 5, 1999 entitled “Control System for Multi-Phase Brushless DC Motor”; U.S. Pat. No. 5,309,347 to Poma et al., issued May 3, 1994, entitled “H-Bridge Circuit with Protection Against Crossover Conduction”; U.S. Pat. No. 6,943,514 to Chen et al., issued Sep. 13, 2005, entitled “Motor Control Circuit for Supplying a Controllable Driving Current”; U.S. Pat. No. 6,131,692 to Kawasuji, issued Oct. 17, 2000, entitled “Electric Power Steering Controller”; and U.S. Application Publication No. 2005/0127859 to Kernhof et al., filed Dec. 13, 2004, entitled “32V H-Bridge Driver with CMOS Circuits”.
Modern configurable electronic controllers, such as the one described in U.S. Pat. No. 7,096,073, include a multiplicity of input-cells for measuring various types of input sensors and a multiplicity of output-cells for driving and controlling various types of output devices. Such output-cells can be configured to form an H-Bridge module and control circuitry of the types discussed above. The multiplicity of output cells dictates a practical need to minimize the controller's complexity and size, especially in larger industrial systems, an issue having direct bearing on space, cost and reliability of the control device, especially in mass production. There is, therefore, a need to design better modular and more compact circuitry for current protection mechanism and load current sensing (value and direction), serving H-Bridge load control designs.